Originally posted by lgreen 1. I don't want to stretch the envelope re the heat. You see the size of my heatsinks (8.7" high, 8" long, 1.5" deep x 4) how much pwr should I go for? I'm not looking to run this on the edge of thermal capacity, 40-60 WPC is fine.

3. What value of R should I use in my Power supply, CRC filter? Per rail it will be 60,000uF --- R --- 60,000 uF. 8x60,0000 uf Caps total. I've simulated the PS on the PSU designer but not sure of the load etc... I am not going to attempt a CLC filter.

5. how the heck does one connect big wires to the spikes on my diode bridges (shown in the pic at the far ends)? is there a std connector for this?

1) If these sinks are 2 per channel, then I don't see any problem
with the 60W figure.

3) .5 ohm is a typical figure, but you want it in the 10+ wattage
size.

I to am starting the aleph x but i'm going with the mini version and lower power nothing over 20 watts. I am still amazed how these mini a's sound @ 20 watts.. i wonder if ill hear any difference with the aleph x's

I have time for 3/4 day of hitting the high end at Alexis park. Will take pics if I remember to get more batteries for the camera. Its my buddie's 40th birthday and it just happened by a fluke to be during CES. We all have "industry" affiliations to get in.

I never tried the amp without input caps after reading Peter Daniels reports quite a long time ago.

When you use unbalanced dc-coupled connections you will load both inputs differently.

Since I wanted to mate it to an X-BOSOZ wich has a small amount of dc-output depending on the input (thanks to the X-resistors wich are dc-coupled) I never further investigated.

William

JENSEN TRANSFORMERS (look on their site white paper etc)have an interesting but simple way to create a balanced output from a single ended pre with only an addition of a resistor and a cap.You could add these to the output of your preamp or even the input of the ax.
I find the sound with this mod much better in my system.There should nor really be a difference but there is.
I am using an aikido pre and it is a huge difference from the bosoz/bls even xbls.It gives all the advantages of tubed sound but with the power of the ax .I was also using before a well designed opamp pre with AD8610 /current sources/output buffers etc but only with the aikido did I get the excellent mid/high transparency that is similar to good set amp.To my ears the bosoz and opamp pre although pretty good were too colored in the long run and I found I was always reverting back to my set amp for most listening.

I'm one of the proud owners of a AX but when i put my ear in the bass speaker i hear some hum. It's not much and normally you don't hear it but i don't like it.
When i measure with a scope at the output i see a few millivolt 100 hz products(see picture; timebase 2ms/div and input 10mv/div).
When i measure the rail voltage i see 30mv tt ripple.

The ax's are monoblocks with CLC filtering(44.000uF-2,2mH-44.000uF per rail, so 176.000uF total per monoamp)
Rail voltage is around 19 volts and the idle current is 6,6A

I read something about turning the transformer and i try this a bit but it's almost impossible with 4x2,5mm secondary.
B.t.w. it's no input hum and in low power mode(2,2A idle current) i need a stethoscope to hear it.

Is it usual to have some hum under these conditions?
More capacitors? or inductive problems?

Mine acts the same way but I don't bother since I can't hear it when the music plays. It seems to be a common problem with many AX's and I suspect that only meticulous design, component choice and layout as in the stock Aleph's can cure the problem. I still wonder how Nelson manages to get a hum level in the µV range.

Mine acts the same way ... I still wonder how Nelson manages to get a hum level in the µV range.

/Hugo

Hi Hugo,

I'm "happy" you have the same"problem". I wonder too how Nelson solve this item.

The strange thing is that i have a "remarkeble" difference between the two monoamps while their contruction is the same and the one with the lowest hum level has the highest ripple.
Strange isn't it ???
I played with the wiring but nothing is sensitive.

The ax-design has not much feedback so it's not amazing that there is some hum but that difference between the two monoamps is still playing around in my mind.

I also read reports of other ax-owners who say that their amp is as quiet as a mouse so what do we wrong??? Or they didn't put a ear in the bass speaker.

You could do a regulator if the filtering is insufficient. However, maybe it is hum being induced from the power supply. A couple of things to try:
1) Shield unshielded transformers with a high nickel content alloy.
2) Use a separate chassis for the power supply, or at least partition the amplifier.
3) Solid state rectifiers create ringing which is far above audio frequency, but it is modulated by the power line frequency, so you have a sort of high frequency carrier RF being induced into your audio circuits, and you hear the 60 Hz modulation in an analogy to AM radio. This is best solved with a snubber; see this article.